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Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectroscopy showed that methylolated kraft lignin has more hydroxymethyl groups than glyoxalated kraft lignin. For the epoxidization reaction we studied the influence of the lignin:NaOH (w/w) ratio, temperature, and time of the reaction on the properties of the prepared epoxidized lignins. The structures of lignin-based epoxy resins were followed by epoxy index test and FTIR spectroscopy. Optimal conditions were obtained for lignin-based epoxy resin produced at lignin/NaOH = 1/3 at 70 ºC for 3h. Thermogravimetry analysis (TGA) revealed that the epoxidization enhances the thermal stability of lignins and may allow a wider temperature range for applications with lignin epoxy-PF blends.

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A novel resin, poly(dimethylsilylene-ethynylene-phenoxyphenoxyphenylene-ethynylene), was synthesized from 1,4-bis( p-ethynylphenoxy)benzene and dimethyldichlorosilane through Grignard reaction. The structures of the monomer and the resin were characterized by elemental analysis, Fourier transform infrared, proton nuclear magnetic resonance, electron ionization-mass spectrometry and gel permeation chromatography. The thermal behaviour of the resin was examined by differential scanning calorimetry. The cured resin exhibits excellent dielectric property, high glass transition temperature, good mechanical properties and high thermal stability. The flexural strength and impact strength of the cured resin were 55.0 MPa and 10.5 KJ m−2, respectively. The degradation temperature at 5% weight loss of the cured resin arrived at 549°C in nitrogen.